Hypophosphatemia in postoperative patients with total parenteral nutrition: influence of nutritional support teams

PURPOSE, SETTING AND SUBJECTS: We conducted a prospective, descriptive study of postoperative patients under total parenteral nutrition controlled by a Multidisciplinary Nutritional Support Team in a tertiary care hospital. Between january 2002 and november 2003. Data of nutritional status, nutritional support, hypophosphatemia, electrolyte and metabolic complications were reviewed.

RESULTS

215 postoperative patients (63.3% male, 68 +/- 13.9 years old, 47.4% neoplasia). were included. Nutritional support according nutritional needs was made during fasting 14.2 +/- 18.4 days. Mild-moderate initial malnutrition was present in 58% of patients. 18.1% developed postoperative hypophosphatemia 96 hours after starting total parenteral nutrition containing phosphate. 37.7% patients showed moderated and 6.5% severe hypophosphatemia. Nutritional intervention corrected hypophosphatemia (p < 0.001). Factors related to hypophosphatemia were hypokalemia, hypomagnesemia, hypercalcemia, female sex, neoplasia, 96-hour postoperative period and duration of nutrition.

CONCLUSIONS

Prevalence of hypophosphatemia in postoperative patients with total parenteral nutrition is high and needs timely monitoring. The intervention of Multidisciplinary Nutritional Support Team is effective detecting and correcting postoperative hypophosphatemia.

Dynamic left ventricular outflow tract obstruction secondary to catecholamine excess in a normal ventricle

Hypertrophic cardiomyopathy (HCM) is the most common cause of left ventricular outflow tract (LVOT) obstruction. The LVOT obstruction is a consequence of the asymmetric septal hypertrophy and the mitral systolic anterior motion (SAM), causing both of them a dynamic gradient in LVOT. LVOT obstruction has been observed also in other conditions like hypertensive hypertrophy, dehydration, sepsis, vasodilatation, excessive sympathetic stimulation, pericardial tamponade, and after mitral valve repair and aortic valve replacement for aortic stenosis. We report in this document the case of two patients who developed a significant gradient at LVOT in the context of amine treatment during their admission into the intensive unit care. In both, cases there were no gradient, significant hypertrophy or SAM at baseline cardiac evaluation. We have met only one case reported in the literature matching those conditions. In order to treat this type of patients properly, it is essential to take in consideration this pathology.

Factors influencing medical treatment of heart failure patients in Spanish internal medicine departments: a national survey

BACKGROUND

The medical management of heart failure (HF) in clinical practice varies considerably by country and by medical specialty.

AIM

To assess the treatment of HF patients admitted to Internal Medicine departments, and to evaluate out-patient management prior to admission, by specialty.

DESIGN

Prospective cross-sectional multi-centre survey.

METHODS

Of 55 randomly selected Spanish hospitals, 51 agreed to participate. All patients (n = 2145) consecutively admitted for decompensated HF to the Departments of Internal Medicine of these hospitals, over 5 months, were included. Twenty variables were analysed, including aspects relating to out-patient management prior to admission.

RESULTS

Mean +/- SD age was 77.2 +/- 10.5 years, 57.3% were female, 47% had systolic dysfunction. Prescriptions at discharge: loop diuretics 85.6%, spironolactone 29.8%, ACEIs 65.8%, beta-blockers 8.7%, cardiac glycosides 39%. At admission, 86% already had a diagnosis of HF. Of these, 53% (older patients and more women) were being treated on an out-patient basis by primary care physicians. Primary care physicians requested fewer echocardiograms than internists (38% vs. 69%, p<0.001) and prescribed fewer drugs (ACEIs 40% vs. 54%, p<0.001; spironolactone 15% vs. 23%, p<0.05; beta-blockers 6% vs. 13%, p<0.01). The internists treated more incapacitated patients than the cardiologists (p<0.001), prescribed more high-dose ACEIs (20% vs. 13%, p<0.01) and spironolactone (26% vs. 20%, p<0.05), and fewer anticoagulants (32% vs. 39%, p<0.05).

DISCUSSION

Patients admitted to medical departments with HF are different to those found in clinical trials. Their management is currently suboptimal. Differences in treatment between internists and cardiologists appear to be accounted for by differences in the patients they treat.

Calcineurin-independent inhibition of mitochondrial Ca2+ uptake by cyclosporin A

1. Cyclosporin A (CsA) is a widely used compound because of its potent immunosupressive properties, derived mainly from the inhibition of calcineurin, and also because of its ability to block the mitochondrial permeability transition pore (PTP). This second effect has been involved in the protection against apoptosis mediated by release of mitochondrial factors. We show here that CsA (1-10 microm) has an additional effect on Ca(2+) homeostasis in mitochondria that cannot be attributed to inhibition of PTP. 2. By measuring specifically mitochondrial [Ca(2+)] with targeted aequorin, we show that CsA inhibited Ca(2+) entry into mitochondria both in intact and in permeabilized cells, and this effect was stronger when Ca(2+) entry was triggered by low cytosolic [Ca(2+)], below 5 microm. 3. Inhibition of mitochondrial Ca(2+) uptake required micromolar concentrations of CsA and was not mimicked by other inhibitors of calcineurin such as FK-506 or cypermethrin, nor by a different inhibitor of the PTP, bongkrekic acid. 4. CsA blocked the increase in mitochondrial Ca(2+) uptake rate induced by the mitochondrial Ca(2+) uniporter activator SB202190. 5. Our results suggest that CsA inhibits Ca(2+) entry through the Ca(2+) uniporter by a mechanism independent of the inhibition of PTP or calcineurin. This effect may contribute to reduce depolarization and Ca(2+) overloading in mitochondria after cell stimulation, and thus cooperate with the direct inhibition of PTP to prevent apoptosis.

Measuring [Ca2+] in the endoplasmic reticulum with aequorin

The photoprotein aequorin was the first probe used to measure specifically the [Ca(2+)] inside the lumen of the endoplasmic reticulum ([Ca(2+)](ER)) of intact cells and it provides values for the steady-state [Ca(2+)](ER), around 500 microM, that closely match those obtained now by other procedures. Aequorin-based methods to measure [Ca(2+)](ER) offer several advantages: (i) targeting of the probe is extremely precise; (ii) the use of low Ca(2+)-affinity aequorin allows covering a large dynamic range of [Ca(2+)], from 10(-5) to 10(-3)M; (iii) aequorin is nearly insensitive to changes in Mg(2+) or pH, has a high signal-to-noise ratio and calibration of the results in [Ca(2+)] is made straightforward using a simple algorithm; and (iv) the equipment required for luminescence measurements in cell populations is simple and low-cost. On the negative side, this technique has also some disadvantages: (i) the relatively low amount of emitted light makes difficult performing single-cell imaging studies; (ii) reconstitution of aequorin with coelenterazine requires previous complete depletion of Ca(2+) of the ER for 1-2h, a maneuver that may result in deleterious effects in some cells; (iii) because of the high rate of aequorin consumption at steady-state [Ca(2+)](ER), only relatively brief experiments can be performed; and (iv) expression of ER-targeted aequorin requires previous transfection or infection to introduce the appropriate DNA construct, or alternatively the use of stable cell clones. Choosing aequorin or other techniques to measure [Ca(2+)](ER) will depend of the correct balance between these properties in a particular problem.

[Identification of doctors with high pharmaceutical expenditure]

OBJECTIVE

[corrected] To identify doctors with high pharmaceutical expenditure through multiple regression of variables not exclusively dependent on the doctor's decision. To compare the agreement with the method of the Spanish national health servicem which only considered the percentage of pensioners of the doctor's list.

METHODS

Cross-sectional, retrospective, descriptive study of the pharmaceutical expenditure of 220 general practitioners in the health district of Toledo (Spain) in 1999. The following variables were collected: pharmaceutical expenditure for policy-holder/month (PEP-H); age; sex; habitat; size of the list; percentage of pensioners; frequency of attendance (consults/policy-holder-year) and workload (consultations per day). A multiple regression model with backwards elimination was constructed, taking like PEP-H as the dependent variable and the remaining as the independent variables. The resultant equation enabled calculation of the expected PEP-H for each doctor and the deviation of their real expenditure ofrom the expected. Doctors were considered to have high pharmaceutical expenditure when the deviation was more than the mean plus 1 standard deviation of this distribution.

RESULTS

The mean PEP-H was 2,584.4 pesetas. Differences were found (F = 11.665; p < 0.005) in PEP-H per habitat (2,723.2 in rural, 2,521.4 in semi urban and 2,168.2 in urban). A significant correlation was found (p < 0.005) between PEP-H and percentage of pensioners (r = 0.728) and frequency of attendance (r = 0.607). Our final model included percentage of pensioners, frequency of attendance, and age (F = 102.33; p < 0.005; r = 0.767; r² = 0.588; β = 206.05; β₁ = 48.27; β₂ = 61.26; β₃ = 9.55). This model were identified 25 DHPC. With the INSALUD model the identification were of 31. The Kappa index showed that agreement between both methods was 0.706 (SE 0.056) and simple disagreement was found in the classification of 24 doctors (10.9%).

CONCLUSIONS

Frequency of attendance and the percentage of pensioners on doctors' lists are iclosely related to PEP-H. The indicator currently used by the Spanish national health system to identify doctors with high pharmaceutical expenditure could be improved if other variables, such as frenquency of attendance and the doctors' age, were taken into account. The adoption of this method would make budget allocation more impartial and fair.

Stimulation by thimerosal of histamine-induced Ca(2+) release in intact HeLa cells seen with aequorin targeted to the endoplasmic reticulum

The oxidizing thiol reagent, thimerosal, has been shown to activate reversibly the inositol 1,4,5-trisphosphate (InsP(3)) receptor in several cell types. We have studied here the effects of thimerosal by monitoring the [Ca(2+)] inside the endoplasmic reticulum (ER) of intact HeLa cells with targeted aequorin. We show that thimerosal produced little effects on the ER-Ca(2+)-pump and only slightly increased the ER-Ca(2+)-leak in intact cells. Instead, thimerosal increased the sensitivity to histamine of ER-Ca(2+)-release by about two orders of magnitude, made the response much more prolonged at saturating histamine concentrations and enhanced both cytosolic and mitochondrial [Ca(2+)] responses to histamine. Moreover, inhibition of ER-Ca(2+)release by cytosolic [Ca(2+)] microdomains was fully preserved and sensitive to BAPTA-loading, and histamine-induced Ca(2+) release remained quantal in the presence of both thimerosal and intracellular BAPTA. The effects of thimerosal were reversible in the presence of dithiotreitol, suggesting the possible presence of a physiological redox regulatory mechanism. However, in permeabilized cells thimerosal potentiated InsP(3)-induced Ca(2+) release but oxidized glutathione had no effect. In addition, thimerosal increased the [Ca(2+)](ER) steady-state level in permeabilized cells. Thimerosal partially inhibited also plasma membrane Ca(2+)extrusion and increased Ca(2+)(Mn(2+)) entry through the plasma membrane, both phenomena contributing to increase the steady-state cytosolic [Ca(2+)]. Thimerosal-induced Ca(2+) entry was additive to that induced by emptying of the ER, suggesting that store-operated Ca(2+) channels may not be involved. These results provide new insights on the mechanisms of activation and inactivation of InsP(3) receptors.

Integrated random processes exhibiting long tails, finite moments, and power-law spectra

A dynamical model based on a continuous addition of colored shot noises is presented. The resulting process is colored and non-Gaussian. A general expression for the characteristic function of the process is obtained, which, after a scaling assumption, takes on a form that is the basis of the results derived in the rest of the paper. One of these is an expansion for the cumulants, which are all finite, subject to mild conditions on the functions defining the process. This is in contrast with the Lévy distribution--which can be obtained from our model in certain limits--which has no finite moments. The evaluation of the spectral density and the form of the probability density function in the tails of the distribution shows that the model exhibits a power-law spectrum and long tails in a natural way. A careful analysis of the characteristic function shows that it may be separated into a part representing a Lévy process together with another part representing the deviation of our model from the Lévy process. This allows our process to be viewed as a generalization of the Lévy process that has finite moments.

Molecular cloning of the RPS0 gene from Candida tropicalis

The Saccharomyces cerevisiae RPS0 A and B genes encode proteins essential for maturation of the 40S ribosomal subunit precursors. We have isolated a homologue of the RPS0 gene from Candida tropicalis, which we named CtRPS0. The C. tropicalis RPS0 encodes a protein of 261 amino acid residues with a predicted molecular weight of 28.65 kDa and an isoelectric point of 4.79. CtRps0p displays significant amino acid sequence homology with Rps0p from C. albicans, S. cerevisiae, Neurospora crassa, Schizosaccharomyces pombe, Pneumocystis carinii and higher organisms, such as human, mouse and rat. CtRPS0 on a high copy number vector can complement the lethal phenotype linked to the disruption of both RPS0 genes in S. cerevisiae. Southern blot analysis suggests that CtRPS0 is present at a single locus within the C. tropicalis genome.

Control of secretion by mitochondria depends on the size of the local [Ca2+] after chromaffin cell stimulation

In chromaffin cells, plasma membrane calcium (Ca2+) channels and mitochondria constitute defined functional units controlling the availability of Ca2+ nearby exocytotic sites. We show here that, when L-/N-type Ca2+ channels were inhibited with nisoldipine and omega-conotoxin GVIA, cytosolic [Ca2+] ([Ca2+]c) peaks measured in fura-4F-loaded cells were reduced by 36%; however, mitochondrial Ca2+ uptake was unaffected and secretion was potentiated by protonophores as in control cells. By contrast, when non L-type Ca2+ channels were inhibited with omega-conotoxin MVIIC, [Ca2+]c peaks induced by high K+ were reduced by 73%, mitochondrial Ca2+ uptake was abolished, and secretion was not modified by protonophores. However, if Ca2+ entered only through L-type channels activated by FPL64176, high K+ stimulation induced fast mitochondrial Ca2+ uptake and catecholamine secretion was strongly increased and potentiated by protonophores. These results confirm the close association of catecholamine secretion to mitochondrial Ca2+ uptake, and indicate the sharp threshold of local [Ca2+]c (about 5 microM) required for triggering fast mitochondrial Ca2+ uptake that is able to modulate secretion. The entry of Ca2+ through L-type channels generated local [Ca2+]c increases just below that, inducing little mitochondrial Ca2+ uptake unless FPL64176 was present. By contrast, Ca2+ entry through P/Q-type channels fully activated mitochondrial Ca2+ uptake. Control of secretion by mitochondria therefore depends critically on the ability of the stimulus to create large local [Ca2+]c microdomains.

Agenesis of the scrotum

Congenital agenesis of the scrotum skin is an extremely rare disorder with only two cases previously reported. We report a newborn with scrotal agenesis and congenital hypothyroidism.

Subjective effects and tolerability of the South American psychoactive beverage Ayahuasca in healthy volunteers

RATIONALE

Ayahuasca is a South American psychoactive beverage that contains the naturally occurring psychedelic agent N,N-dimethyltryptamine (DMT). This "tea" has been used for centuries in religious and medicinal contexts in the rain forest areas of South America and is presently gaining the attention of psychedelic users in North America and Europe.

OBJECTIVES

In the present study, the psychological effects and tolerability of ayvahuasca were assessed.

METHODS

Three increasing doses of encapsulated freeze-dried ayahuasca (0.5, 0.75, and 1.0 mg DMT/kg body weight) were administered to six healthy male volunteers with prior experience in the use of this tea, in a single-blind crossover placebo-controlled clinical trial.

RESULTS

Ayahuasca produced significant dose-dependent increases in five of the six subscales of the Hallucinogen Rating Scale, in the LSD, MBG, and A scales of the Addiction Research Center Inventory, and in the "liking", "good effects" and "high" visual analogue scales. Psychological effects were first noted after 30-60 min, peaked between 60-120 min, and were resolved by 240 min. The tea was well tolerated from a cardiovascular point of view, with a trend toward increase for systolic blood pressure. Modified physical sensations and nausea were the most frequently reported somatic-dysphoric effects. The overall experience was regarded as pleasant and satisfactory by five of the six volunteers, while one volunteer experienced an intensely dysphoric reaction with transient disorientation and anxiety at the medium dose and voluntarily withdrew from the study.

CONCLUSIONS

Ayahuasca can be described as inducing changes in the perceptual, affective, cognitive, and somatic spheres, with a combination of stimulatory and visual psychoactive effects of longer duration and milder intensity than those previously reported for intravenously administered DMT.

[Clinical patterns of soft-tissue sarcoma in children]

INTRODUCTION AND OBJECTIVES

Soft tissue sarcomas are rare mesenchymal neoplasms that constitute less than 10% of all pediatric malignancies. Half of these are rhabdomyosarcomas, the remaining 50% have a varied and heterogenous histologic and clinical patterns (fibrosarcoma, synovial cell sarcoma, extraskeletal Ewing's sarcoma, angiosarcoma, liposarcoma, leiomyosarcoma, ...). The purpose of this work is to evaluate our clinical experience with soft tissue sarcomas in uncommon sites over the past 10 years in order to delimitate the prognostic factors in survival and modalities of treatment.

MATERIAL AND METHODS

Between 1989 and 1998, 10 patients were diagnosed with soft tissue sarcomas in uncommon sites and treated by us over a total number of 139 pediatric neoplasms (7.19%). Data on these patients were obtained from careful review of medical records. Variables investigated included histologic findings, tumor size, age at presentation, primary site, clinical group, radiologic test performed, surgical treatment, radiotherapy and adjuvant chemotherapy, complications and survival rates. Charts were registered in database Access. Statistical analysis was performed by the SPSS 8.0 statistical program.

RESULTS

The following histologic types of these 10 tumors were identified: 1 hemangiopericytoma in oral cavity, 2 extraosseous Ewing's sarcoma, 1 botryoid rhabdomyosarcoma of the bladder, 1 mediastinal fibrosarcoma, 1 retroperitoneal rhabdomyosarcoma, 1 paratesticular rhabdomyosarcoma, 1 cervical condrosarcoma, 1 alveolar rhabdomyosarcoma and 1 deltoid rhabdomyosarcoma. 50% were rhabdomyosarcomas and the remaining 50% have a variated sarcomatous histologic pattern with a difficult classification. The mean age at diagnosis was 7 years (4.6 years accounted for rhabdomyosarcoma alone). Surgery with complete excision were performed only in six cases. Adjuvant chemotherapy with IVA was followed by radiotherapy only in four patients. All the children classified in clinical groups II, III or IV needed 2nd. line regimens of chemotherapy. Three patients died in the follow-up instead of the multimodal treatment. Survival ranged from 6 months to 9 years (mean 4 years).

CONCLUSIONS

The impact of surgical resectability on outcome in these tumors has been clearly demonstrated over other factors like histologic appearance. Distant metastasis are infrequent but local recurrence are a constant in all cases with incomplete surgical resection. Based on those facts we could advanced an adequate approach to this kind of neoplasms: 1) wide complete surgical resection is mandatory; 2) radiotherapy will only be necessary if margins of resection cannot control the local disease, and 3) chemotherapy have not clearly demonstrated his benefits as adjuvant therapy in clinical group I lesions but his employ is recommended in all cases because of the poor prognosis due to local recurrence.

Mitochondrial Ca(2+)-induced Ca(2+) release mediated by the Ca(2+) uniporter

We have reported that a population of chromaffin cell mitochondria takes up large amounts of Ca(2+) during cell stimulation. The present study focuses on the pathways for mitochondrial Ca(2+) efflux. Treatment with protonophores before cell stimulation abolished mitochondrial Ca(2+) uptake and increased the cytosolic [Ca(2+)] ([Ca(2+)](c)) peak induced by the stimulus. Instead, when protonophores were added after cell stimulation, they did not modify [Ca(2+)](c) kinetics and inhibited Ca(2+) release from Ca(2+)-loaded mitochondria. This effect was due to inhibition of mitochondrial Na(+)/Ca(2+) exchange, because blocking this system with CGP37157 produced no further effect. Increasing extramitochondrial [Ca(2+)](c) triggered fast Ca(2+) release from these depolarized Ca(2+)-loaded mitochondria, both in intact or permeabilized cells. These effects of protonophores were mimicked by valinomycin, but not by nigericin. The observed mitochondrial Ca(2+)-induced Ca(2+) release response was insensitive to cyclosporin A and CGP37157 but fully blocked by ruthenium red, suggesting that it may be mediated by reversal of the Ca(2+) uniporter. This novel kind of mitochondrial Ca(2+)-induced Ca(2+) release might contribute to Ca(2+) clearance from mitochondria that become depolarized during Ca(2+) overload.

[Isolated primary hyperaldosteronism caused by adrenocortical carcinoma]

OBJECTIVE

To report a case of adrenocortical carcinoma and primary aldosteronism as the sole endocrine manifestation.

METHODS/RESULTS

A 39-year-old male with adrenocortical carcinoma and primary aldosteronism is presented. Following complete hormonal and radiological evaluation, right adrenalectomy and nephrectomy were performed (pT2pN0M0, stage II). Blood pressure, serum potassium and aldosterone levels returned to normal. The patient received adjuvant therapy with carboplatin and etoposide. After 15 months' disease-free interval, lung metastasis was diagnosed, without evidence of local recurrence until 5 months later, when hypertension and primary hyperaldosteronism reappeared. There were no other endocrine disorders. Treatment with spironolactone, 5-FU and adriamycin was instituted with no tumor response and the patient died 3 years later from complications of endobronchial metastasis.

CONCLUSION

Adrenocortical carcinoma with isolated primary hyperaldosteronism is uncommon and consequently there is no wide experience in regard to its diagnosis and treatment. Although randomized studies are not available, adjuvant therapy using other agents instead of mitotane (o,p-DDD), such as the combination of cisplatin and etoposide (VP-16), seems reasonable in the locally advanced stages. Mitotane may be useful when hypercortisolism is present, but its efficacy as an antitumor agent has been controversial.

Molecular evolution of the growth hormone-releasing hormone/pituitary adenylate cyclase-activating polypeptide gene family. Functional implication in the regulation of growth hormone secretion

Growth hormone-releasing hormone (GHRH) and pituitary adenylate cyclase-activating polypeptide (PACAP) belong to the same superfamily of regulatory neuropeptides and have both been characterized on the basis of their hypophysiotropic activities. This review describes the molecular evolution of the GHRH/PACAP gene family from urochordates to mammals and presents the hypothesis that the respective roles of GHRH and PACAP in the control of GH secretion are totally inverted in phylogenetically distant groups of vertebrates. In mammals, GHRH and PACAP originate from distinct precursors whereas, in all submammalian taxa investigated so far, including birds, amphibians and fish, a single precursor encompasses a GHRH-like peptide and PACAP. In mammals, GHRH-containing neurons are confined to the infundibular and dorsomedial nuclei of the hypothalamus while PACAP-producing neurons are widely distributed in hypothalamic and extrahypothalamic areas. In fish, both GHRH- and PACAP-immunoreactive neurons are restricted to the diencephalon and directly innervate the adenohypophysis. In mammals and birds, GHRH plays a predominant role in the control of GH secretion. In amphibians, both GHRH and PACAP are potent stimulators of GH release. In fish, PACAP strongly activates GH release whereas GHRH has little or no effect on GH secretion. The GHRH/PACAP family of peptides thus provides a unique model in which to investigate the structural and functional facets of evolution.

[Contraindications for the endoscopic treatment of vesicoureteral reflux]

The endoscopic treatment of vesicoureteral reflux (VUR) has acquired a great importance as a therapeutic option during the last years. We present our experience with two substances, teflon paste and macroplastic, used in 86 patients, with 147 refluxing renal units. After first injection, the successful rate was 86% for teflon pastes versus 91% for macroplastic in the middle grade VUR units. We analyze our complications rates (14.25%) and we conclude that there is a close relation with a right technic performance. In our experience we consider a major contraindication for this technical option patients less than 1 year of life. At the same time we presume that an special care must be taken in monorenal patients as well.

[Atrioventricular nodal reentrant tachycardia as a trigger for atrial fibrillation]

We report the case of a 43 year-old male with a long history of paroxysmal palpitations aborted by vagal manoeuvres, where atrial fibrillation was the only documented arrhythmia. During the electrophysiological study an AV nodal reentrant tachycardia was demonstrated with rapid degeneration into atrial fibrillation. After slow pathway ablation, nodal tachycardia became non-inducible. No palpitations were reported and no arrhythmic event was recorded after a follow-up of 20 months. In selected cases, the electrophysiological study could reveal potentially curable causes of atrial fibrillation.

A method for the selection of the optimum counting conditions in a ZnS(Ag) scintillation detector

The well-known criteria for the selection of the optimum counting conditions in a ZnS(Ag) scintillation detector seem to restrict its applicability. These do not consider simultaneously operating voltage and electronic threshold variation to reach the best counting conditions. Therefore, a more general method for the determination of the optimum counting conditions in ZnS(Ag) scintillation detectors is proposed. In this method, a relationship between voltage and electronic threshold is derived for counting efficiency. In order to test the method, quality control procedures have been carried out as well as the determination of gross alpha activity in environmental samples.

Chromaffin-cell stimulation triggers fast millimolar mitochondrial Ca2+ transients that modulate secretion

Activation of calcium-ion (Ca2+) channels on the plasma membrane and on intracellular Ca2+ stores, such as the endoplasmic reticulum, generates local transient increases in the cytosolic Ca2+ concentration that induce Ca2+ uptake by neighbouring mitochondria. Here, by using mitochondrially targeted aequorin proteins with different Ca2+ affinities, we show that half of the chromaffin-cell mitochondria exhibit surprisingly rapid millimolar Ca2+ transients upon stimulation of cells with acetylcholine, caffeine or high concentrations of potassium ions. Our results show a tight functional coupling of voltage-dependent Ca2+ channels on the plasma membrane, ryanodine receptors on the endoplasmic reticulum, and mitochondria. Cell stimulation generates localized Ca2+ transients, with Ca2+ concentrations above 20-40 microM, at these functional units. Protonophores abolish mitochondrial Ca2+ uptake and increase stimulated secretion of catecholamines by three- to fivefold. These results indicate that mitochondria modulate secretion by controlling the availability of Ca2+ for exocytosis.

[A comparative study of the treatment of vesicoureteral reflux in childhood: a review of a series of 636 refluxing units]

A number of 411 pediatric patients (636 refluxing renal units) diagnosed as having vesicoureteral reflux (VUR) were evaluated in our Hospital between 1985 and 1997. All the patients were divided in two historic groups based on the therapeutical modalities employed. The children included in group A (between 1985 and 1995) were medically or surgically treated according to the grade of reflux. In the group B (between 1995 and 1997), the endoscopic treatment was added to previous. All cases underwent urine cultures, renal ultrasonography, voiding cystourethrography and isotopic gammagraphy with DMSA scan. In some patients were performed radionuclide renography with DTPA or MAG-3 to assess renal function. We consider that medical management is required in low grade reflux (I and II) but patients with high grade reflux (IV and V) clearly benefit from early ureteral surgical reimplantation (Cohen technique). In our series, patients with reflux grade III are treated endoscopically with Teflon or PDMS (polydimethylsiloxane) with resolution of reflux in 82-92% after first injection.